Brain scans show that people who have had Botox injections have altered brain activity when they look at happy and angry faces, possibly because the paralysis of muscles means they can’t mimic the expressions they see.

After having Botox injections in the forehead, people’s brains respond in a different way when they see images of faces showing emotion. This may mean they find it harder to interpret other people’s emotions because of disrupted signalling between their facial muscles and their brains.

Brain scans showed that Botox injected into the forehead altered people’s brain chemistry, impacting how they interpreted other people’s emotions, a new study published in Scientific Reports found.

Botox is an injectable that temporarily reduces or eliminates facial fine lines and wrinkles and is popularly used to reduce the appearance of frown lines, forehead creases and crow’s feet near the eyes.

According to the American Society of Plastic Surgeons, the US recorded 4,401,536 Botulinum Toxin Type A procedures, which includes Botox and similar products, in 2020 — the year with the most recent data.

Botox injections have increased by 459% since 2000, becoming the most common minimally invasive cosmetic procedure.

As more and more people across the country continue to schedule appointments to get Botox, researchers questioned how the temporary paralysis of the facial muscles that results from the treatment impacts a person’s ability to interpret emotions.

Researchers at the University of California Irvine and AbbVie, a biotech company that makes Botox, conducted functional magnetic resonance imaging scans on 10 women between the ages of 33 and 40.

Brain scans were performed both before the women received Botox injections in their forehead and again two to three weeks after to compare the brain’s reactions to emotive images.

During the two scans, the women were shown photos of happy, angry and neutral faces and asked to interpret the emotion being expressed.

The researchers found that after receiving Botox, the women’s brain activity was altered in their amygdala (a part of the brain involved in the experiencing of emotions) when they looked at angry and happy faces, and in the fusiform gyrus (a key structure for functionally specialized computations of high-level vision such as face perception, object recognition and reading) when they looked at happy ones.

As the researchers expected, these findings align with the facial feedback hypothesis, which claims that people instinctively mirror facial expressions in an effort to identify and experience the emotion being expressed in front of them.

The researchers note that the temporary paralysis of the facial muscles caused by Botox hinders a person’s ability to mirror the emotions being expressed in front of them, thereby altering their brain chemistry as they attempt to interpret the emotions.